Commits · e6fa8a79fe03e1734c26287474b1ac09287fdeb7 · Kirill Smelkov / linux

27 Sep, 2022 21 commits

migrate_pages(): fix failure counting for THP splitting · e6fa8a79

Huang Ying authored Aug 17, 2022

If THP is failed to be migrated, it may be split and retry.  But after
splitting, the head page will be left in "from" list, although THP
migration failure has been counted already.  If the head page is failed to
be migrated too, the failure will be counted twice incorrectly.  So this
is fixed in this patch via moving the head page of THP after splitting to
"thp_split_pages" too.

Link: https://lkml.kernel.org/r/20220817081408.513338-7-ying.huang@intel.com
Fixes: 5984fabb ("mm: move_pages: report the number of non-attempted pages")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

e6fa8a79

migrate_pages(): fix failure counting for THP on -ENOSYS · 577be05c

Huang Ying authored Aug 17, 2022

If THP or hugetlbfs page migration isn't supported, unmap_and_move() or
unmap_and_move_huge_page() will return -ENOSYS.  For THP, splitting will
be tried, but if splitting doesn't succeed, the THP will be left in "from"
list wrongly.  If some other pages are retried, the THP migration failure
will counted again.  This is fixed via moving the failure THP from "from"
to "ret_pages".

Another issue of the original code is that the unsupported failure
processing isn't consistent between THP and hugetlbfs page.  Make them
consistent in this patch to make the code easier to be understood too.

Link: https://lkml.kernel.org/r/20220817081408.513338-6-ying.huang@intel.com
Fixes: 5984fabb ("mm: move_pages: report the number of non-attempted pages")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

577be05c

migrate_pages(): fix failure counting for THP subpages retrying · 5fc30916

Huang Ying authored Aug 17, 2022

If THP is failed to be migrated for -ENOSYS and -ENOMEM, the THP will be
split into thp_split_pages, and after other pages are migrated, pages in
thp_split_pages will be migrated with no_subpage_counting == true, because
its failure have been counted already.  If some pages in thp_split_pages
are retried during migration, we should not count their failure if
no_subpage_counting == true too.  This is done this patch to fix the
failure counting for THP subpages retrying.

Link: https://lkml.kernel.org/r/20220817081408.513338-5-ying.huang@intel.com
Fixes: 5984fabb ("mm: move_pages: report the number of non-attempted pages")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

5fc30916

migrate_pages(): fix THP failure counting for -ENOMEM · fbed53b4

Huang Ying authored Aug 17, 2022

In unmap_and_move(), if the new THP cannot be allocated, -ENOMEM will be
returned, and migrate_pages() will try to split the THP unless "reason" is
MR_NUMA_MISPLACED (that is, nosplit == true).  But when nosplit == true,
the THP migration failure will not be counted.

This is incorrect, so in this patch, the THP migration failure will be
counted for -ENOMEM regardless of nosplit is true or false.  The nr_failed
counting isn't fixed because it's not used.  Added some comments for it
per Baolin's suggestion.

Link: https://lkml.kernel.org/r/20220817081408.513338-4-ying.huang@intel.com
Fixes: 5984fabb ("mm: move_pages: report the number of non-attempted pages")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fbed53b4

migrate_pages(): remove unnecessary list_safe_reset_next() · 9c62ff00

Huang Ying authored Aug 17, 2022

Before commit b5bade97 ("mm: migrate: fix the return value of
migrate_pages()"), the tail pages of THP will be put in the "from"
list directly.  So one of the loop cursors (page2) needs to be reset,
as is done in try_split_thp() via list_safe_reset_next().  But after
the commit, the tail pages of THP will be put in a dedicated
list (thp_split_pages).  That is, the "from" list will not be changed
during splitting.  So, it's unnecessary to call list_safe_reset_next()
anymore.

This is a code cleanup, no functionality changes are expected.

Link: https://lkml.kernel.org/r/20220817081408.513338-3-ying.huang@intel.comSigned-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

9c62ff00

migrate: fix syscall move_pages() return value for failure · a7504ed1

Huang Ying authored Aug 17, 2022

Patch series "migrate_pages(): fix several bugs in error path", v3.

During review the code of migrate_pages() and build a test program for
it.  Several bugs in error path are identified and fixed in this
series.

Most patches are tested via

- Apply error-inject.patch in Linux kernel
- Compile test-migrate.c (with -lnuma)
- Test with test-migrate.sh

error-inject.patch, test-migrate.c, and test-migrate.sh are as below.
It turns out that error injection is an important tool to fix bugs in
error path.


This patch (of 8):

The return value of move_pages() syscall is incorrect when counting
the remaining pages to be migrated.  For example, for the following
test program,

"
 #define _GNU_SOURCE

 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <errno.h>

 #include <fcntl.h>
 #include <sys/uio.h>
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <numaif.h>
 #include <numa.h>

 #ifndef MADV_FREE
 #define MADV_FREE	8		/* free pages only if memory pressure */
 #endif

 #define ONE_MB		(1024 * 1024)
 #define MAP_SIZE	(16 * ONE_MB)
 #define THP_SIZE	(2 * ONE_MB)
 #define THP_MASK	(THP_SIZE - 1)

 #define ERR_EXIT_ON(cond, msg)					\
	 do {							\
		 int __cond_in_macro = (cond);			\
		 if (__cond_in_macro)				\
			 error_exit(__cond_in_macro, (msg));	\
	 } while (0)

 void error_msg(int ret, int nr, int *status, const char *msg)
 {
	 int i;

	 fprintf(stderr, "Error: %s, ret : %d, error: %s\n",
		 msg, ret, strerror(errno));

	 if (!nr)
		 return;
	 fprintf(stderr, "status: ");
	 for (i = 0; i < nr; i++)
		 fprintf(stderr, "%d ", status[i]);
	 fprintf(stderr, "\n");
 }

 void error_exit(int ret, const char *msg)
 {
	 error_msg(ret, 0, NULL, msg);
	 exit(1);
 }

 int page_size;

 bool do_vmsplice;
 bool do_thp;

 static int pipe_fds[2];
 void *addr;
 char *pn;
 char *pn1;
 void *pages[2];
 int status[2];

 void prepare()
 {
	 int ret;
	 struct iovec iov;

	 if (addr) {
		 munmap(addr, MAP_SIZE);
		 close(pipe_fds[0]);
		 close(pipe_fds[1]);
	 }

	 ret = pipe(pipe_fds);
	 ERR_EXIT_ON(ret, "pipe");

	 addr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
	 ERR_EXIT_ON(addr == MAP_FAILED, "mmap");
	 if (do_thp) {
		 ret = madvise(addr, MAP_SIZE, MADV_HUGEPAGE);
		 ERR_EXIT_ON(ret, "advise hugepage");
	 }

	 pn = (char *)(((unsigned long)addr + THP_SIZE) & ~THP_MASK);
	 pn1 = pn + THP_SIZE;
	 pages[0] = pn;
	 pages[1] = pn1;
	 *pn = 1;

	 if (do_vmsplice) {
		 iov.iov_base = pn;
		 iov.iov_len = page_size;
		 ret = vmsplice(pipe_fds[1], &iov, 1, 0);
		 ERR_EXIT_ON(ret < 0, "vmsplice");
	 }

	 status[0] = status[1] = 1024;
 }

 void test_migrate()
 {
	 int ret;
	 int nodes[2] = { 1, 1 };
	 pid_t pid = getpid();

	 prepare();
	 ret = move_pages(pid, 1, pages, nodes, status, MPOL_MF_MOVE_ALL);
	 error_msg(ret, 1, status, "move 1 page");

	 prepare();
	 ret = move_pages(pid, 2, pages, nodes, status, MPOL_MF_MOVE_ALL);
	 error_msg(ret, 2, status, "move 2 pages, page 1 not mapped");

	 prepare();
	 *pn1 = 1;
	 ret = move_pages(pid, 2, pages, nodes, status, MPOL_MF_MOVE_ALL);
	 error_msg(ret, 2, status, "move 2 pages");

	 prepare();
	 *pn1 = 1;
	 nodes[1] = 0;
	 ret = move_pages(pid, 2, pages, nodes, status, MPOL_MF_MOVE_ALL);
	 error_msg(ret, 2, status, "move 2 pages, page 1 to node 0");
 }

 int main(int argc, char *argv[])
 {
	 numa_run_on_node(0);
	 page_size = getpagesize();

	 test_migrate();

	 fprintf(stderr, "\nMake page 0 cannot be migrated:\n");
	 do_vmsplice = true;
	 test_migrate();

	 fprintf(stderr, "\nTest THP:\n");
	 do_thp = true;
	 do_vmsplice = false;
	 test_migrate();

	 fprintf(stderr, "\nTHP: make page 0 cannot be migrated:\n");
	 do_vmsplice = true;
	 test_migrate();

	 return 0;
 }
"

The output of the current kernel is,

"
Error: move 1 page, ret : 0, error: Success
status: 1
Error: move 2 pages, page 1 not mapped, ret : 0, error: Success
status: 1 -14
Error: move 2 pages, ret : 0, error: Success
status: 1 1
Error: move 2 pages, page 1 to node 0, ret : 0, error: Success
status: 1 0

Make page 0 cannot be migrated:
Error: move 1 page, ret : 0, error: Success
status: 1024
Error: move 2 pages, page 1 not mapped, ret : 1, error: Success
status: 1024 -14
Error: move 2 pages, ret : 0, error: Success
status: 1024 1024
Error: move 2 pages, page 1 to node 0, ret : 1, error: Success
status: 1024 1024
"

While the expected output is,

"
Error: move 1 page, ret : 0, error: Success
status: 1
Error: move 2 pages, page 1 not mapped, ret : 0, error: Success
status: 1 -14
Error: move 2 pages, ret : 0, error: Success
status: 1 1
Error: move 2 pages, page 1 to node 0, ret : 0, error: Success
status: 1 0

Make page 0 cannot be migrated:
Error: move 1 page, ret : 1, error: Success
status: 1024
Error: move 2 pages, page 1 not mapped, ret : 1, error: Success
status: 1024 -14
Error: move 2 pages, ret : 1, error: Success
status: 1024 1024
Error: move 2 pages, page 1 to node 0, ret : 2, error: Success
status: 1024 1024
"

Fix this via correcting the remaining pages counting.  With the fix,
the output for the test program as above is expected.

Link: https://lkml.kernel.org/r/20220817081408.513338-1-ying.huang@intel.com
Link: https://lkml.kernel.org/r/20220817081408.513338-2-ying.huang@intel.com
Fixes: 5984fabb ("mm: move_pages: report the number of non-attempted pages")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

a7504ed1

filemap: make the accounting of thrashing more consistent · f347c9d2

Yang Yang authored Aug 05, 2022

Once upon a time, we only support accounting thrashing of page cache. 
Then Joonsoo introduced workingset detection for anonymous pages and we
gained the ability to account thrashing of them[1].

So let delayacct account both the thrashing of page cache and anonymous
pages, this could make the codes more consistent and simpler.

[1] commit aae466b0 ("mm/swap: implement workingset detection for anonymous LRU")

Link: https://lkml.kernel.org/r/20220805033838.1714674-1-yang.yang29@zte.com.cnSigned-off-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>